diff --git a/Propellor/CmdLine.hs b/Propellor/CmdLine.hs
index 1f99288..516bb5c 100644
--- a/Propellor/CmdLine.hs
+++ b/Propellor/CmdLine.hs
@@ -103,7 +103,7 @@ pullFirst cmdline next = do
 	newsha <- getCurrentGitSha1 branchref
 
 	if oldsha == newsha
-		then next
+		then error "unchanged"
 		else do
 			putStrLn "Rebuilding propeller.."
 			hFlush stdout